Conventionally, low volume and mid-volume copiers and image input terminals utilize moving scanning carriages to scan an image. These moving scanning carriages usually include an illumination device like a fluorescent lamp. These scanning carriages are moved across an image by a cable system during the scanning process. Such a prior art scanning carriage system is illustrated in FIG. 1. This scanning system is commonly called a half rate/full rate scanning system.
In FIG. 1, a motor 1 in conjunction with a belt 3 is used to drive a capstan 5. Capstan 5 has a plurality of cable windings around it such that when the capstan 5 is rotated, certain cable strands are pulled onto the capstan and other cable strands are released from the capstan. As illustrated in FIG. 1, two sets of cables 11 and 13 are used to move a lamp carriage 17 and a mirror carriage 19 having corner mirrors 21 positioned thereon.
Cable 11 is connected to the frame 9 by anchor 10. The cable 11 is then wrapped around pulley (roller) 57 and connected to the lamp carriage 17 through clamp 28. From clamp 28, cable 11 is wrapped around pulleys (rollers) 51 and 50 before being wrapped around, capstan 5. The remaining portion of cable 11 wraps around pulleys (rollers) 55, 60, 58, and 59 before being connected to spring 8. Spring 8 is connected to the frame 9 by anchor 6. Cable 11 is connected to the mirror carriage 19 at pulleys (rollers) 57 and 58.
Cable 13 is connected to the frame 9 by anchor 2. The cable 13 is then wrapped around pulley (roller) 52 and connected to the lamp carriage 17 through clamp 27. From clamp 27, cable 13 is wrapped around pulley (roller) 50 before being wrapped around capstan 5. The remaining portion of cable 13 wraps around pulleys (rollers) 54, 53, and 56 before being connected to spring 4. Spring 4 is connected to the frame 9 by anchor 6. Cable 13 is connected to the mirror carriage 19 at pulleys (rollers) 52 and 53.
The cables 11 and 13 are wrapped around the pulleys (rollers) in such a configuration that when the cables 11 and 13 are released or pulled onto the capstan 5, the carriages 17 and 19 are properly moved to scan the image. More specifically, a lamp 15 which is located on the lamp carriage 17 provides a light source to scan the image wherein the light reflected from the image is incident upon mirrors located on the lamp carriage 19 and thus are directed toward corner mirrors 21 located on the mirror carriage 19. The corner mirrors 21 direct the reflected light from the mirror on the lamp carriage 19 to a lens. The lens focuses the scanned image onto a CCD or full width array sensor. The sensor converts the reflected light into electrical signals representing the scanned image.
This scanning operation can be more clearly seen in FIG. 2 of the present application. FIG. 2 illustrates the path of light as it is reflected from the image 101. The reflected light, as noted above, is incident upon a mirror 117 which is located on the lamp carriage 17. This mirror 117 then directs the light towards the corner mirrors 21 on the mirror carriage which causes the light to make a 180.degree. turn. The light leaving the corner mirrors 21 is directed to an optical lens assembly 107 which focuses the reflected light upon a CCD or full width sensor array 109.
The utilization of pulleys on the mirror carriage 19 allows the mirror carriage to move into proper proportion to the movement of the lamp carriage 17. In other words, a focused image is maintained by maintaining a certain fixed optical distance between the image 101 and the lens 107 while the lamp carriage 17 is moving. The fixed optical length is ensured by the mirror carriage 19 moving at exactly one half the speed of the lamp carriage 17 and in the same direction as the lamp carriage 17.
It is desirable to produce full color images with digital scanners. To produce a full color image, the light reflected from the image must be filtered by at least three color filters so as to produce three sets of color image data. Although digital scanners have been able to achieve this result, the result has only been achieved by redesigning the entire scanning system which increases the cost of producing a color scanner. The mirror system described above does not aid in the color separation process. Thus, it is desirable to provide a retrofit to a monochrome digital scanner's scanning system which easily converts the monochrome scanner to a full color digital scanner.